Experimental dielectronic recombination rate coefficients for lithium-like ⁴⁰Ca¹⁷⁺

Abstract

The rate coefficients for dielectronic recombination (DR) of lithium-like 40Ca17+ ions with ∆n = 0 core excitations are derived from electron-ion recombination spectra measured with merged-beams method at the heavy-ion storage ring CSRm. The experimental DR spectrum, in the electron-ion collision energy range of 0 to 42 eV in the center-of-mass frame, comprises of all DR resonance peaks belong to the 2s 2S1/2 → 2p 2P1/2, 3/2 core excitations. The resonant energies and strengths for the resolved resonances in 2pjnl series are determined by fitting of the measured DR peaks. The further interpretation of the measured DR rate coefficients has been performed by calculating the DR rate coefficients with relativistic configuration-interaction method implemented in Flexible Atomic Code (FAC) and compared with the experimental results. The experimental results and FAC calculations are found to be in a good agreement within the experimental uncertainties. Moreover, temperature dependent plasma rate coefficients were constructed from 4×103 to 1×107 K energy region by convoluting experimental and theoretical DR rate coefficients with the Maxwellian energy distribution function and then compared with previously available data. The plasma DR rate coefficient is found to be significantly underestimated by the early theoretical data calculated by Jacobs et al., and Mazotta et al in the low temperature. In contrast, a very good agreement has been found between the theoretical DR data of Gu and Colgan et al and the presently measured results at the low temperature region. Therefore, the results in this work composed of a bench-mark data set for plasma modeling at the photoionized temperature range. We have also provided a fit to our measured and theoretical plasma rate coefficients for low temperature plasma modeling.

Absolute dielectronic recombination rate coefficients of highly charged ions at the storage ring CSRm and CSRe

“…Since the first calibration DR experiment with Lilike Ar 15+ ions at the CSRm in 2015, [20] DR rate coefficients of a series of HCIs, including 40 Ar 12+,13+,14+ , [21][22][23] 40 Ca 14+,16+,17+ , [24][25][26] 58 Ni 19+ , [28] 112 Sn 35+ , [31] and 073401-2…”

“…Ar 12+ [21] Ar 14+ [23] Ca 14+ [24] Ca 16+ [25] Ca 17+ [26] Ni 19+ [28] Kr 25+ [29] c 1 2.20 [ All the datasets presented in this paper, including the fitting parameters of the experimentally derived field-ionizationfree PRRC for the Ar 12+,14+ , Ca 14+,16+,17+ , Ni 19+ , and Kr 25+ ions measured at the HIRFL-CSR are compiled in the supplementary materials in PDF format.…”

“…More recently, the main cooler storage ring (CSRm) and the experimental cooler storage ring (CSRe) at the Heavy Ion Research Facility in Lanzhou (HIRFL) started contributing DR rate coefficients for HCIs. Recombination experiments with 36 Ar 15+ , 40 Ar 12+,13+,14+,15+ , 40 Ca 14+,16+,17+ , 56 Fe 17+ , 58 Ni 19+ , and 76 Kr 25+ ions [20][21][22][23][24][25][26][27][28][29] have been accomplished at the CSRm in the past few years, and the first calibration experiment with Na-like Kr 25+ ions has been successfully performed at the CSRe. [30] In this paper, the recent progress on DR experiments at the HIRFL-CSRm and CSRe is overviewed.…”

Atomic structure and collision dynamics with highly charged ions

“…[41] In the past few years, a series of DR experiments for different HCIs have been investigated at the CSR, such as Ar 12+,13+,14+,15+ , Ca 14+,16+,17+ , Ni 19+ , and Kr 25+ ions, electron correlations are studied. [39,41,42,45,[47][48][49] In addition, a large accelerator facility of High-Intensity heavy-ion Accelerator Facility (HIAF) [50] is being under construction by the Institute of Modern Physics at Huizhou city in Guangdong Province. The DR spectroscopy of highly charged ions by employing an electron cooler and an independent ultra-cold electron target is listed as one of the main scientific goals of HIAF project, the detailed description can be found in Refs.…”

“…In particular, Li-, Be-, B-, and C-like argon and calcium ions have been systematically investigated. [39,42,[47][48][49]120] Iron ions are the most abundant heavy elements in the universe and the ions with different charge states are of special interests to astrophysical plasma studies, therefore, corresponding experimental work on DR of Fe (7−14)+ and Fe (18−22)+ ions has been carried out at the storage ring TSR over already more than one decade. The experimental data resulting from this effort are summarized and has been published in Ref.…”